Displays of this type are known from EP 1 529 274 and EP 1 090 384. In these known displays, piezo actuators are used as the actuating drives, which move the movable walls like a micropump and thus press colored liquid into the color levels or move a clear, transparent, and colorless fluid into the color levels. Magnets may also be used as the actuating drives. The known displays have the disadvantage that their actuating drives are not controllable or are only controllable with difficulty during a control and are therefore not suitable for filling the color levels with colored liquid by one-half, one-third, one-fourth, or another fraction. The partial filling of the color levels with colored liquids of the colors red, green, blue or cyan, magenta, yellow is necessary to achieve as many finely graduated color tones as possible of the pixels.
Furthermore, transporting the colored liquid from the color reservoir into the color level and out of the color level into the color reservoir with the aid of so-called electro-wetting technology is known. Multiple layers must be applied to the transparent wall, in particular an electrode layer and an insulating layer. A fluid layer, which is composed of two liquids which are not miscible with one another, e.g., an oily colored liquid and colorless water, is typically moved using the electro-wetting technology so that a clear, transparent, colorless liquid or a colored liquid is transported into the color levels of a pixel.
These electrodes and layers are applied as ultrathin, transparent layers, but nonetheless these layers obstruct the passage of light, because light beams are deflected and refracted on the edges of these layers. Scattered light partially results, so that the light transparency of the walls of the color levels which are coated to provide the required electrodes is not optically pure. This interferes in particular if three or four color levels of a pixel are situated one behind another. The partial filling of the color levels with colored liquid with the aid of the electro-wetting technology is also only possible with great expenditure and not with the desired rapidity.
Accordingly, it would be desirable to provide an actuating drive for a micropump or the movable wall of the color reservoir, which may be controlled in such a way that precise intermediate positions are also possible.